Valuable resins are known which can be prepared by basically reacting an unsaturated acid such as acrylic acid with each of the epoxide groups of a polyepoxide. In many instances it is desirable to dissolve this resin in a copolymerizable monomer such as styrene for making reinforced plastics or various acrylate esters when formulating radiation polymerizable compositions. From a practical standpoint the choice of monomers is sometimes limited because certain monomers may be too volatile or too toxic, have an undesirable odor, etc. to be useful under the conditions employed. For example, inks which are curable by ultraviolet light may be unable to use toxic or highly volatile momomers because of the hazards they would produce to people who would be using the inks. However, certain of these monomers may be very desirable from the standpoint of the properties they would add to the cured product. This invention makes it possible to obtain at least partial benefit from such monomers by modifying the above resin under controlled production conditions where the hazards involved can be safely handled.
For other reasons, part of the acrylic acid and like reactant has been replaced in one instance by an acid terminated unsaturated polyester as disclosed in U.S. Pat. No. 3,506,736 or in a second instance by a carboxyl terminated rubber as disclosed in Ser. No. 343,716, filed on Mar. 21, 1973 by D. J. Najvar, now U.S. Pat. No. 3,892,819. However, this invention concerns another method of modifying the resins for a different purpose and with beneficial results.